Let I, Ea, Eb, Ec be the incenter and the excenters of ABC. Let Iaa, Iab, Iac be the excenters of IBC opposite to the angles I, B, C. Define analogously Ibb, Ibc, Iba, Icc, Ica, Icb. The Brocard lines of the triangles IaIabIac, IbIbcIba, IcIcaIcb concur.